Jeff
you're right about longboarders making great classic fish riders as far as smoothness.
The two smoothest I'm seen so far making the transition would include Beau Young along in Aus and here in Hawaii there's an ultra smooth old school young kid longboarder named David Banquil who tears it up on a fish as well. At Haubush they teasingly call him the "Chocolate Joel Tudor". You can see him fishing it up in his self made DVD "The Coconut Technique". I still remember seeing him tear up town and white plains on his little yellow fish wearing those big white surf goggles from oakley.